The second face of this idea is especially destructive. It is the conflation of disagreement and hate. It no longer can tell the difference between two people having a difference of opinion and the emotion of malice of one toward the other. Once we unpack this problem, we see it also creates an ad hoc barrier between a person and knowledge. If knowledge is, roughly speaking, a justified grasp of reality, and people reduce their differences to expressions of an emotion they have ruled out the deeper possibility of reaching an accurate grasp of an idea. They have necessarily ruled out the truth of the matter helping to settle the disagreement.
As an interesting note to the current sociological expression of this idea, the hate is only perceived in one direction. Imagine a teacher and student disagreeing over the answer to, "5+7." Applying the current form of this idea about belief, the student is able to dismiss the possibility of him being wrong about the sum, and chalk the whole thing up to his teacher's hatred of him. But, in a destructive twist of irony, the teacher (who is right) is not able to apply the same emotional standard to the student - she is not allowed to say the student simply hates her. This is not only a hypocritical standard of judgment, it is deeply destructive in that is shields a person from what really matters - the truth of the matter.
We normally don't get angry with each other over the sum, "5+7." We do get angry with each other over moral and spiritual matters. So, in order to address this conflation of emotion and disagreement, I want to use the math example as a guide to talking about deeper things. We think (generally speaking), the student would be wrong to conclude their answer of "13" is their emotional right, and that the teacher is simply expressing hate when she tells him he is wrong. And we think this we because we still have (though it is arguably corroding) a sense that math and science are both knowable truths by everyone no matter their culture or background. In other words, math and science are objectively knowable and applicable to all people. The difference, then, between how we handle mathematical sums and moral judgments is in our belief about their truth value.
If mathematical truths are "out there," then we can all talk about them knowing that we are not casting personal aspersions toward each other when we disagree. "Only emotionally unstable terrorists believe 5+7=13!" We know, on some level, the truth of the matter is not up to us but is up to the universe - we know reality constitutes truth. We have, however, accepted the claim that moral and religious truths are not "out there," but rather are within us - we are the makers of our own moral and religious truths. Thus, when we disagree we are not appealing to an objective third thing, we are disagreeing on a personal level.
If this is true, one solution is to recapture the better sense of what makes moral and religious claims true or false - reality itself. If we do this, then at least on one important level we have removed the truth-maker of religious claims from personal preference and put it back where it belongs. Either God exists or he doesn't. Either God was in Christ reconciling the world to himself or he wasn't. These are claims on reality not on what sooths my psychological make-up.
Now none of this addresses an individual's emotions when they discuss differences of belief. After all, the things we believe about religion and morality are usually very deep and important things to us and it can be easy to be emotionally invested in them. But it disconnects the truth of the matter from how you or I feel about it! Putting claims like, "God exists" back in the realm of public knowledge gives us really good reasons to reject the current cultural trend of projecting distasteful emotions upon people with whom we disagree.
I encourage you to reject this poison and refuse to engage in this kind of immature dialogue. Talk about the truth with wisdom and love instead, trying to draw nearer to the truth yourself and help others along the journey.